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Ongoing projects

Binational Studies
 

San Diego State University is located at the border between, USA and Mexico on Kumeyaay land in a diversity hotspot. Our lab studies serves these communities by studying species with binational distribution that have ecological and cultural value. We study how the Anthropocene is impacting these plants.


Along with Dr. Sula Vanderplank we run the Binational Studies Program https://binationalstudies.wixsite.com/internship

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Students from the 2021-2022 cohort in the Binational Studies Program

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We have a collaborative project supported by NSF- Bridging Ecology and Evolution project with Drs. Seema Sheth (North Carolina State University), Chris Muir (U of Hawaiʻi), Jeff Diez (U of Oregon), and Jay Sexton (UC Merced). We will bridge evolutionary approaches with population ecology models by investigating whether evolution can rescue populations of scarlet monkeyflowers from decline when they encounter rapid environmental change. We will address the following goals about how the  probability of evolutionary rescue varies across a species’ range:​

  1. Quantify natural selection in contrasting environments by linking traits, fitness components, and population growth,

  2. Assess the extent to which the breeder’s equation predicts realized rates of trait evolution across the species’ range, and

  3. Determine where in the species’ range evolutionary rescue is most likely based on standing genetic variation for fitness.

To address these objectives, we will perform a resurrection study comparing ancestors and descendants derived from seed collected before and after a period of severe drought and heat in western North America. We will transplant seedlings from leading-edge, central, and trailing-edge populations of the perennial herb, Erythranthe cardinalis, into three common gardens at differing range positions and quantify natural selection on traits, additive genetic variances for traits and fitness, and differences in population growth rates and traits between ancestors and descendants. 

Hybridization

Reticulate evolution by hybridization is considered a common process shaping the evolution of many plant species, however, reticulation could also be due to incomplete lineage sorting in biodiverse systems. 

We study reticulate evolution in a variety of plant groups such as Pinus, Eucalyptus, Arbutusetc. using a variety of approaches such as genetics/genomics, morphology, phenology, physiology and ecology.  

Evolution of reproductive systems

We are interested in understanding the evolution of reproductive systems in plants and their ecological consequences. The presence of cosexual and unisexual individuals in sympatry allowed us to test evolutionary hypotheses to sexual separation such as inbreeding depression and sexual allocation and to explore the consequences of sexual separation on herbivory patterns.

We also study the bisexuality which has been proposed to be an innovation of angiosperms but the development of bisporangiate cones in Pinus allowed us to show that mechanisms for producing bisexual structures predates the angiosperm – gymnosperm split and also has provided insights of the ancestral state of angiosperms. 

Bisporangiate strobilus (also called bisexual cone) of Pinus johannis at the time of pollination.

We study how climate change disrupts reproduction, for example pollen viability and phenology, testing the hypothesis that lower elevation populations, experiencing higher temperatures will be more adapted to heat stress, differences that will be reflected at the vegetative and reproductive level, providing the genetic material to higher elevation populations to allow them to cope with climate change.

We study the flower development in dioecious species, the cellular and genetic mechanisms that remodels hermaphroditic flowers into unisexual.

Abnormal development of anthers of female flowers of Opuntia spp.

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Resilient Restoration: Advancing Ecological, Cultural and Community Resilience with Tribal Communities in Southern California supported by the California SGC Climate Change Research Program.

See project's webpage here

The Transnational Approaches to Sustainable Food Futures: Integrated High-Impact Learning Experiences and Pathways to Food Careers project is supported by the USDA-NIFA HSI program.

It is run in collaboration with Drs. Pascale Joassart-Marcelli, Ramona Perez, Changqi Liu, John Love, Stephen Welter from SDSU and Waverly Ray from Mesa College. It is part of the projects supporting the Center for Better Food Futures.

We are offering scholarship to support students joining our program.  More information can be found here.

Our lab is involved training students on the how to use edible native plants and sustainable practices to preserve our biodiversity hotspot.

This project is linked to the new multidisciplinary course CAL-400. 

Eucalyptus

In collaboration with Dr. Markus Riegler and his team (Hawkesbury Institute of Environment) we study the widespread and ongoing defoliation of Grey Box (Eucalyptus moluccana), caused by the outbreak of jumping plant-lice (Psyllidae), which has resulted in extensive canopy dieback and tree mortality. Grey box is a foundation species widely distributed in the woodlands of eastern Australia.

 

This outbreak might be exacerbated by global warming in association with genetic diversity depletion, due to deforestation causing a genetic bottleneck. We are testing this hypothesis using molecular and ecological methods. We have compared genetic variation along multiple populations with varying degrees of defoliation. We are interested in understanding the environmental, genetic and chemical contributions to the Grey Box-psyllid interaction, its dynamics and the implications for forest health. We have contrasted the genetic patterns to morphological leaf diversity along a latitudinal gradient to understand the adaptive response to defoliation. 

Pinus strobiformis

This is a multi-institutional and binational collaborative project supported by NSF-macrosystems in collaboration with Drs. Kristen Waring, Amy Whipple, Samuel Cushman, Andrew Eckert, Chris Still and Christian Wehenkel that explores the genetic and epigenetic contribution to the susceptibility to infection and mortality in Pinus strobiformis caused by the non-native, invasive forest pathogen (Cronartium ribicola) exacerbated by climate change. Restriction-site associated DNA sequencing (RADSeq) is being used to estimate the dynamics of gene flow, population structure and hybridization to better understand the temporal and geographic patterns of susceptibility to both the pathogen and drought on P. strobiformis.

For more info please click here

Pinus edulis

In collaboration with Drs. Catherine Gehring, Amy Whipple and Thomas Whittham (Northern Arizona University) we examined the importance of soil microbes to the growth and survival of a widespread pine under drought conditions. We found that specific beneficial fungus–host genotype combinations promoted drought tolerance in field and greenhouse studies. Drought tolerance, and associations with particular fungi, were passed from mother trees to their offspring, indicating the traits are genetic. These results demonstrate the interlinked importance of the genetics of a tree and its microbiome, which can be used to restore forest losses resulting from drought.

See article in PNAS here and in the news here.

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